Spatiotemporal intermittency and localized dynamic fluctuations upon approaching the glass transition

TL;DR

This paper introduces a new method to analyze spatial and temporal heterogeneity in systems approaching the glass transition, revealing localized dynamic fluctuations in simulated and experimental systems.

Contribution

It presents a robust approach for characterizing dynamic fluctuations across different scales and applies it to both simulations and experiments near the glass transition.

Findings

Localized dynamic fluctuations mark the onset of glassiness.

Regions of correlated mobile particles contain tens to hundreds of particles.

The method removes trivial system size dependence of fluctuations.

Abstract

We introduce a new and robust approach for characterizing spatially and temporally heterogeneous behavior within a system based on the evolution of dynamic fuctuations once averaged over different space lengths and time scales. We apply it to investigate the dynamics in two canonical systems as the glass transition is approached: simulated Lennard-Jones liquids and experimental dense colloidal suspensions. We find that in both cases the onset of glassines is marked by spatially localized dynamic fluctuations originating in regions of correlated mobile particles. By removing the trivial system size dependence of the fluctuations we show that such regions contain tens to hundreds of particles for time scales corresponding to maximally non-Gaussian dynamics.